| Abstract: | We describe the use of a package of subroutines for general-relativistic algebraic computations written in the LISP-based algebraic programming system REDUCE developed by Anthony Hearn. The first group of routines calculates concomitants of the metric tensor such as the Riemann tensor, Ricci tensor, Ricci scalar, Einstein tensor and Weyl tensor from given covariant or covariant and contravariant metric tensor components. One of these procedures includes the evaluation of the Maxwell equations and invariants as well as the Maxwell energy momentum tensor. A second group of routines takes the components of a null tetrad as input and evaluates the null frame projections of the Riemann tensor, the Einstein tensor as well as – if required – the 14 local invariants of the Riemann tensor. It also includes a determination of the Petrov type. Perturbation calculations may be performed and run effectively. The output can be presented in a flexible format chosen according to the needs of the user. A number of further special-purpose programs are available on request. The article should enable a reader familar with General Relativity but unfamilar with formula manipulating system, to employ the package. |
